1 //! Defines how the compiler represents types internally.
3 //! Two important entities in this module are:
5 //! - [`rustc_middle::ty::Ty`], used to represent the semantics of a type.
6 //! - [`rustc_middle::ty::TyCtxt`], the central data structure in the compiler.
8 //! For more information, see ["The `ty` module: representing types"] in the ructc-dev-guide.
10 //! ["The `ty` module: representing types"]: https://rustc-dev-guide.rust-lang.org/ty.html
12 pub use self::fold::{FallibleTypeFolder, TypeFoldable, TypeFolder, TypeVisitor};
13 pub use self::AssocItemContainer::*;
14 pub use self::BorrowKind::*;
15 pub use self::IntVarValue::*;
16 pub use self::Variance::*;
22 use crate::metadata::ModChild;
23 use crate::middle::privacy::AccessLevels;
24 use crate::mir::{Body, GeneratorLayout};
25 use crate::traits::{self, Reveal};
27 use crate::ty::subst::{GenericArg, InternalSubsts, Subst, SubstsRef};
28 use crate::ty::util::Discr;
30 use rustc_attr as attr;
31 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
32 use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
33 use rustc_data_structures::tagged_ptr::CopyTaggedPtr;
35 use rustc_hir::def::{CtorKind, CtorOf, DefKind, Res};
36 use rustc_hir::def_id::{CrateNum, DefId, LocalDefId, LocalDefIdMap, CRATE_DEF_INDEX};
38 use rustc_macros::HashStable;
39 use rustc_query_system::ich::StableHashingContext;
40 use rustc_session::cstore::CrateStoreDyn;
41 use rustc_span::symbol::{kw, Ident, Symbol};
42 use rustc_span::{sym, Span};
43 use rustc_target::abi::Align;
45 use std::cmp::Ordering;
46 use std::collections::BTreeMap;
47 use std::hash::{Hash, Hasher};
48 use std::ops::ControlFlow;
49 use std::{fmt, ptr, str};
51 pub use crate::ty::diagnostics::*;
52 pub use rustc_type_ir::InferTy::*;
53 pub use rustc_type_ir::*;
55 pub use self::binding::BindingMode;
56 pub use self::binding::BindingMode::*;
57 pub use self::closure::{
58 is_ancestor_or_same_capture, place_to_string_for_capture, BorrowKind, CaptureInfo,
59 CapturedPlace, ClosureKind, MinCaptureInformationMap, MinCaptureList,
60 RootVariableMinCaptureList, UpvarCapture, UpvarCaptureMap, UpvarId, UpvarListMap, UpvarPath,
63 pub use self::consts::{Const, ConstInt, ConstKind, InferConst, ScalarInt, Unevaluated, ValTree};
64 pub use self::context::{
65 tls, CanonicalUserType, CanonicalUserTypeAnnotation, CanonicalUserTypeAnnotations,
66 CtxtInterners, DelaySpanBugEmitted, FreeRegionInfo, GeneratorInteriorTypeCause, GlobalCtxt,
67 Lift, OnDiskCache, TyCtxt, TypeckResults, UserType, UserTypeAnnotationIndex,
69 pub use self::instance::{Instance, InstanceDef};
70 pub use self::list::List;
71 pub use self::sty::BoundRegionKind::*;
72 pub use self::sty::RegionKind::*;
73 pub use self::sty::TyKind::*;
75 Binder, BoundRegion, BoundRegionKind, BoundTy, BoundTyKind, BoundVar, BoundVariableKind,
76 CanonicalPolyFnSig, ClosureSubsts, ClosureSubstsParts, ConstVid, EarlyBoundRegion,
77 ExistentialPredicate, ExistentialProjection, ExistentialTraitRef, FnSig, FreeRegion, GenSig,
78 GeneratorSubsts, GeneratorSubstsParts, InlineConstSubsts, InlineConstSubstsParts, ParamConst,
79 ParamTy, PolyExistentialProjection, PolyExistentialTraitRef, PolyFnSig, PolyGenSig,
80 PolyTraitRef, ProjectionTy, Region, RegionKind, RegionVid, TraitRef, TyKind, TypeAndMut,
81 UpvarSubsts, VarianceDiagInfo,
83 pub use self::trait_def::TraitDef;
94 pub mod inhabitedness;
96 pub mod normalize_erasing_regions;
117 mod structural_impls;
122 pub type RegisteredTools = FxHashSet<Ident>;
125 pub struct ResolverOutputs {
126 pub definitions: rustc_hir::definitions::Definitions,
127 pub cstore: Box<CrateStoreDyn>,
128 pub visibilities: FxHashMap<LocalDefId, Visibility>,
129 pub access_levels: AccessLevels,
130 pub extern_crate_map: FxHashMap<LocalDefId, CrateNum>,
131 pub maybe_unused_trait_imports: FxHashSet<LocalDefId>,
132 pub maybe_unused_extern_crates: Vec<(LocalDefId, Span)>,
133 pub reexport_map: FxHashMap<LocalDefId, Vec<ModChild>>,
134 pub glob_map: FxHashMap<LocalDefId, FxHashSet<Symbol>>,
135 /// Extern prelude entries. The value is `true` if the entry was introduced
136 /// via `extern crate` item and not `--extern` option or compiler built-in.
137 pub extern_prelude: FxHashMap<Symbol, bool>,
138 pub main_def: Option<MainDefinition>,
139 pub trait_impls: BTreeMap<DefId, Vec<LocalDefId>>,
140 /// A list of proc macro LocalDefIds, written out in the order in which
141 /// they are declared in the static array generated by proc_macro_harness.
142 pub proc_macros: Vec<LocalDefId>,
143 /// Mapping from ident span to path span for paths that don't exist as written, but that
144 /// exist under `std`. For example, wrote `str::from_utf8` instead of `std::str::from_utf8`.
145 pub confused_type_with_std_module: FxHashMap<Span, Span>,
146 pub registered_tools: RegisteredTools,
149 #[derive(Clone, Copy, Debug)]
150 pub struct MainDefinition {
151 pub res: Res<ast::NodeId>,
156 impl MainDefinition {
157 pub fn opt_fn_def_id(self) -> Option<DefId> {
158 if let Res::Def(DefKind::Fn, def_id) = self.res { Some(def_id) } else { None }
162 /// The "header" of an impl is everything outside the body: a Self type, a trait
163 /// ref (in the case of a trait impl), and a set of predicates (from the
164 /// bounds / where-clauses).
165 #[derive(Clone, Debug, TypeFoldable)]
166 pub struct ImplHeader<'tcx> {
167 pub impl_def_id: DefId,
168 pub self_ty: Ty<'tcx>,
169 pub trait_ref: Option<TraitRef<'tcx>>,
170 pub predicates: Vec<Predicate<'tcx>>,
185 pub enum ImplPolarity {
186 /// `impl Trait for Type`
188 /// `impl !Trait for Type`
190 /// `#[rustc_reservation_impl] impl Trait for Type`
192 /// This is a "stability hack", not a real Rust feature.
193 /// See #64631 for details.
198 /// Flips polarity by turning `Positive` into `Negative` and `Negative` into `Positive`.
199 pub fn flip(&self) -> Option<ImplPolarity> {
201 ImplPolarity::Positive => Some(ImplPolarity::Negative),
202 ImplPolarity::Negative => Some(ImplPolarity::Positive),
203 ImplPolarity::Reservation => None,
208 impl fmt::Display for ImplPolarity {
209 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
211 Self::Positive => f.write_str("positive"),
212 Self::Negative => f.write_str("negative"),
213 Self::Reservation => f.write_str("reservation"),
218 #[derive(Clone, Debug, PartialEq, Eq, Copy, Hash, TyEncodable, TyDecodable, HashStable)]
219 pub enum Visibility {
220 /// Visible everywhere (including in other crates).
222 /// Visible only in the given crate-local module.
224 /// Not visible anywhere in the local crate. This is the visibility of private external items.
228 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable, TyEncodable, TyDecodable)]
229 pub enum BoundConstness {
232 /// `T: ~const Trait`
234 /// Requires resolving to const only when we are in a const context.
238 impl BoundConstness {
239 /// Reduce `self` and `constness` to two possible combined states instead of four.
240 pub fn and(&mut self, constness: hir::Constness) -> hir::Constness {
241 match (constness, self) {
242 (hir::Constness::Const, BoundConstness::ConstIfConst) => hir::Constness::Const,
244 *this = BoundConstness::NotConst;
245 hir::Constness::NotConst
251 impl fmt::Display for BoundConstness {
252 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
254 Self::NotConst => f.write_str("normal"),
255 Self::ConstIfConst => f.write_str("`~const`"),
272 pub struct ClosureSizeProfileData<'tcx> {
273 /// Tuple containing the types of closure captures before the feature `capture_disjoint_fields`
274 pub before_feature_tys: Ty<'tcx>,
275 /// Tuple containing the types of closure captures after the feature `capture_disjoint_fields`
276 pub after_feature_tys: Ty<'tcx>,
279 pub trait DefIdTree: Copy {
280 fn parent(self, id: DefId) -> Option<DefId>;
282 fn is_descendant_of(self, mut descendant: DefId, ancestor: DefId) -> bool {
283 if descendant.krate != ancestor.krate {
287 while descendant != ancestor {
288 match self.parent(descendant) {
289 Some(parent) => descendant = parent,
290 None => return false,
297 impl<'tcx> DefIdTree for TyCtxt<'tcx> {
298 fn parent(self, id: DefId) -> Option<DefId> {
299 self.def_key(id).parent.map(|index| DefId { index, ..id })
304 pub fn from_hir(visibility: &hir::Visibility<'_>, id: hir::HirId, tcx: TyCtxt<'_>) -> Self {
305 match visibility.node {
306 hir::VisibilityKind::Public => Visibility::Public,
307 hir::VisibilityKind::Crate(_) => Visibility::Restricted(DefId::local(CRATE_DEF_INDEX)),
308 hir::VisibilityKind::Restricted { ref path, .. } => match path.res {
309 // If there is no resolution, `resolve` will have already reported an error, so
310 // assume that the visibility is public to avoid reporting more privacy errors.
311 Res::Err => Visibility::Public,
312 def => Visibility::Restricted(def.def_id()),
314 hir::VisibilityKind::Inherited => {
315 Visibility::Restricted(tcx.parent_module(id).to_def_id())
320 /// Returns `true` if an item with this visibility is accessible from the given block.
321 pub fn is_accessible_from<T: DefIdTree>(self, module: DefId, tree: T) -> bool {
322 let restriction = match self {
323 // Public items are visible everywhere.
324 Visibility::Public => return true,
325 // Private items from other crates are visible nowhere.
326 Visibility::Invisible => return false,
327 // Restricted items are visible in an arbitrary local module.
328 Visibility::Restricted(other) if other.krate != module.krate => return false,
329 Visibility::Restricted(module) => module,
332 tree.is_descendant_of(module, restriction)
335 /// Returns `true` if this visibility is at least as accessible as the given visibility
336 pub fn is_at_least<T: DefIdTree>(self, vis: Visibility, tree: T) -> bool {
337 let vis_restriction = match vis {
338 Visibility::Public => return self == Visibility::Public,
339 Visibility::Invisible => return true,
340 Visibility::Restricted(module) => module,
343 self.is_accessible_from(vis_restriction, tree)
346 // Returns `true` if this item is visible anywhere in the local crate.
347 pub fn is_visible_locally(self) -> bool {
349 Visibility::Public => true,
350 Visibility::Restricted(def_id) => def_id.is_local(),
351 Visibility::Invisible => false,
355 pub fn is_public(self) -> bool {
356 matches!(self, Visibility::Public)
360 /// The crate variances map is computed during typeck and contains the
361 /// variance of every item in the local crate. You should not use it
362 /// directly, because to do so will make your pass dependent on the
363 /// HIR of every item in the local crate. Instead, use
364 /// `tcx.variances_of()` to get the variance for a *particular*
366 #[derive(HashStable, Debug)]
367 pub struct CrateVariancesMap<'tcx> {
368 /// For each item with generics, maps to a vector of the variance
369 /// of its generics. If an item has no generics, it will have no
371 pub variances: FxHashMap<DefId, &'tcx [ty::Variance]>,
374 // Contains information needed to resolve types and (in the future) look up
375 // the types of AST nodes.
376 #[derive(Copy, Clone, PartialEq, Eq, Hash)]
377 pub struct CReaderCacheKey {
378 pub cnum: Option<CrateNum>,
382 /// Represents a type.
384 /// IMPORTANT: Every `TyS` is *required* to have unique contents. The type's
385 /// correctness relies on this, *but it does not enforce it*. Therefore, any
386 /// code that creates a `TyS` must ensure uniqueness itself. In practice this
387 /// is achieved by interning.
388 #[allow(rustc::usage_of_ty_tykind)]
389 pub struct TyS<'tcx> {
390 /// This field shouldn't be used directly and may be removed in the future.
391 /// Use `TyS::kind()` instead.
394 /// This field provides fast access to information that is also contained
397 /// This field shouldn't be used directly and may be removed in the future.
398 /// Use `TyS::flags()` instead.
401 /// This field provides fast access to information that is also contained
404 /// This is a kind of confusing thing: it stores the smallest
407 /// (a) the binder itself captures nothing but
408 /// (b) all the late-bound things within the type are captured
409 /// by some sub-binder.
411 /// So, for a type without any late-bound things, like `u32`, this
412 /// will be *innermost*, because that is the innermost binder that
413 /// captures nothing. But for a type `&'D u32`, where `'D` is a
414 /// late-bound region with De Bruijn index `D`, this would be `D + 1`
415 /// -- the binder itself does not capture `D`, but `D` is captured
416 /// by an inner binder.
418 /// We call this concept an "exclusive" binder `D` because all
419 /// De Bruijn indices within the type are contained within `0..D`
421 outer_exclusive_binder: ty::DebruijnIndex,
424 impl<'tcx> TyS<'tcx> {
425 /// A constructor used only for internal testing.
426 #[allow(rustc::usage_of_ty_tykind)]
427 pub fn make_for_test(
430 outer_exclusive_binder: ty::DebruijnIndex,
432 TyS { kind, flags, outer_exclusive_binder }
436 // `TyS` is used a lot. Make sure it doesn't unintentionally get bigger.
437 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
438 static_assert_size!(TyS<'_>, 40);
440 impl<'tcx> Ord for TyS<'tcx> {
441 fn cmp(&self, other: &TyS<'tcx>) -> Ordering {
442 self.kind().cmp(other.kind())
446 impl<'tcx> PartialOrd for TyS<'tcx> {
447 fn partial_cmp(&self, other: &TyS<'tcx>) -> Option<Ordering> {
448 Some(self.kind().cmp(other.kind()))
452 impl<'tcx> PartialEq for TyS<'tcx> {
454 fn eq(&self, other: &TyS<'tcx>) -> bool {
455 // Pointer equality implies equality (due to the unique contents
460 impl<'tcx> Eq for TyS<'tcx> {}
462 impl<'tcx> Hash for TyS<'tcx> {
463 fn hash<H: Hasher>(&self, s: &mut H) {
464 // Pointer hashing is sufficient (due to the unique contents
466 (self as *const TyS<'_>).hash(s)
470 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for TyS<'tcx> {
471 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
475 // The other fields just provide fast access to information that is
476 // also contained in `kind`, so no need to hash them.
479 outer_exclusive_binder: _,
482 kind.hash_stable(hcx, hasher);
486 #[rustc_diagnostic_item = "Ty"]
487 #[cfg_attr(not(bootstrap), rustc_pass_by_value)]
488 pub type Ty<'tcx> = &'tcx TyS<'tcx>;
490 impl ty::EarlyBoundRegion {
491 /// Does this early bound region have a name? Early bound regions normally
492 /// always have names except when using anonymous lifetimes (`'_`).
493 pub fn has_name(&self) -> bool {
494 self.name != kw::UnderscoreLifetime
499 crate struct PredicateInner<'tcx> {
500 kind: Binder<'tcx, PredicateKind<'tcx>>,
502 /// See the comment for the corresponding field of [TyS].
503 outer_exclusive_binder: ty::DebruijnIndex,
506 #[cfg(all(target_arch = "x86_64", target_pointer_width = "64"))]
507 static_assert_size!(PredicateInner<'_>, 56);
509 #[derive(Clone, Copy, Lift)]
510 pub struct Predicate<'tcx> {
511 inner: &'tcx PredicateInner<'tcx>,
514 impl<'tcx> PartialEq for Predicate<'tcx> {
515 fn eq(&self, other: &Self) -> bool {
516 // `self.kind` is always interned.
517 ptr::eq(self.inner, other.inner)
521 impl Hash for Predicate<'_> {
522 fn hash<H: Hasher>(&self, s: &mut H) {
523 (self.inner as *const PredicateInner<'_>).hash(s)
527 impl<'tcx> Eq for Predicate<'tcx> {}
529 impl<'tcx> Predicate<'tcx> {
530 /// Gets the inner `Binder<'tcx, PredicateKind<'tcx>>`.
532 pub fn kind(self) -> Binder<'tcx, PredicateKind<'tcx>> {
536 /// Flips the polarity of a Predicate.
538 /// Given `T: Trait` predicate it returns `T: !Trait` and given `T: !Trait` returns `T: Trait`.
539 pub fn flip_polarity(&self, tcx: TyCtxt<'tcx>) -> Option<Predicate<'tcx>> {
543 .map_bound(|kind| match kind {
544 PredicateKind::Trait(TraitPredicate { trait_ref, constness, polarity }) => {
545 Some(PredicateKind::Trait(TraitPredicate {
548 polarity: polarity.flip()?,
556 Some(tcx.mk_predicate(kind))
560 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for Predicate<'tcx> {
561 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
565 // The other fields just provide fast access to information that is
566 // also contained in `kind`, so no need to hash them.
568 outer_exclusive_binder: _,
571 kind.hash_stable(hcx, hasher);
575 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
576 #[derive(HashStable, TypeFoldable)]
577 pub enum PredicateKind<'tcx> {
578 /// Corresponds to `where Foo: Bar<A, B, C>`. `Foo` here would be
579 /// the `Self` type of the trait reference and `A`, `B`, and `C`
580 /// would be the type parameters.
581 Trait(TraitPredicate<'tcx>),
584 RegionOutlives(RegionOutlivesPredicate<'tcx>),
587 TypeOutlives(TypeOutlivesPredicate<'tcx>),
589 /// `where <T as TraitRef>::Name == X`, approximately.
590 /// See the `ProjectionPredicate` struct for details.
591 Projection(ProjectionPredicate<'tcx>),
593 /// No syntax: `T` well-formed.
594 WellFormed(GenericArg<'tcx>),
596 /// Trait must be object-safe.
599 /// No direct syntax. May be thought of as `where T: FnFoo<...>`
600 /// for some substitutions `...` and `T` being a closure type.
601 /// Satisfied (or refuted) once we know the closure's kind.
602 ClosureKind(DefId, SubstsRef<'tcx>, ClosureKind),
606 /// This obligation is created most often when we have two
607 /// unresolved type variables and hence don't have enough
608 /// information to process the subtyping obligation yet.
609 Subtype(SubtypePredicate<'tcx>),
611 /// `T1` coerced to `T2`
613 /// Like a subtyping obligation, this is created most often
614 /// when we have two unresolved type variables and hence
615 /// don't have enough information to process the coercion
616 /// obligation yet. At the moment, we actually process coercions
617 /// very much like subtyping and don't handle the full coercion
619 Coerce(CoercePredicate<'tcx>),
621 /// Constant initializer must evaluate successfully.
622 ConstEvaluatable(ty::Unevaluated<'tcx, ()>),
624 /// Constants must be equal. The first component is the const that is expected.
625 ConstEquate(&'tcx Const<'tcx>, &'tcx Const<'tcx>),
627 /// Represents a type found in the environment that we can use for implied bounds.
629 /// Only used for Chalk.
630 TypeWellFormedFromEnv(Ty<'tcx>),
633 /// The crate outlives map is computed during typeck and contains the
634 /// outlives of every item in the local crate. You should not use it
635 /// directly, because to do so will make your pass dependent on the
636 /// HIR of every item in the local crate. Instead, use
637 /// `tcx.inferred_outlives_of()` to get the outlives for a *particular*
639 #[derive(HashStable, Debug)]
640 pub struct CratePredicatesMap<'tcx> {
641 /// For each struct with outlive bounds, maps to a vector of the
642 /// predicate of its outlive bounds. If an item has no outlives
643 /// bounds, it will have no entry.
644 pub predicates: FxHashMap<DefId, &'tcx [(Predicate<'tcx>, Span)]>,
647 impl<'tcx> Predicate<'tcx> {
648 /// Performs a substitution suitable for going from a
649 /// poly-trait-ref to supertraits that must hold if that
650 /// poly-trait-ref holds. This is slightly different from a normal
651 /// substitution in terms of what happens with bound regions. See
652 /// lengthy comment below for details.
653 pub fn subst_supertrait(
656 trait_ref: &ty::PolyTraitRef<'tcx>,
657 ) -> Predicate<'tcx> {
658 // The interaction between HRTB and supertraits is not entirely
659 // obvious. Let me walk you (and myself) through an example.
661 // Let's start with an easy case. Consider two traits:
663 // trait Foo<'a>: Bar<'a,'a> { }
664 // trait Bar<'b,'c> { }
666 // Now, if we have a trait reference `for<'x> T: Foo<'x>`, then
667 // we can deduce that `for<'x> T: Bar<'x,'x>`. Basically, if we
668 // knew that `Foo<'x>` (for any 'x) then we also know that
669 // `Bar<'x,'x>` (for any 'x). This more-or-less falls out from
670 // normal substitution.
672 // In terms of why this is sound, the idea is that whenever there
673 // is an impl of `T:Foo<'a>`, it must show that `T:Bar<'a,'a>`
674 // holds. So if there is an impl of `T:Foo<'a>` that applies to
675 // all `'a`, then we must know that `T:Bar<'a,'a>` holds for all
678 // Another example to be careful of is this:
680 // trait Foo1<'a>: for<'b> Bar1<'a,'b> { }
681 // trait Bar1<'b,'c> { }
683 // Here, if we have `for<'x> T: Foo1<'x>`, then what do we know?
684 // The answer is that we know `for<'x,'b> T: Bar1<'x,'b>`. The
685 // reason is similar to the previous example: any impl of
686 // `T:Foo1<'x>` must show that `for<'b> T: Bar1<'x, 'b>`. So
687 // basically we would want to collapse the bound lifetimes from
688 // the input (`trait_ref`) and the supertraits.
690 // To achieve this in practice is fairly straightforward. Let's
691 // consider the more complicated scenario:
693 // - We start out with `for<'x> T: Foo1<'x>`. In this case, `'x`
694 // has a De Bruijn index of 1. We want to produce `for<'x,'b> T: Bar1<'x,'b>`,
695 // where both `'x` and `'b` would have a DB index of 1.
696 // The substitution from the input trait-ref is therefore going to be
697 // `'a => 'x` (where `'x` has a DB index of 1).
698 // - The supertrait-ref is `for<'b> Bar1<'a,'b>`, where `'a` is an
699 // early-bound parameter and `'b' is a late-bound parameter with a
701 // - If we replace `'a` with `'x` from the input, it too will have
702 // a DB index of 1, and thus we'll have `for<'x,'b> Bar1<'x,'b>`
703 // just as we wanted.
705 // There is only one catch. If we just apply the substitution `'a
706 // => 'x` to `for<'b> Bar1<'a,'b>`, the substitution code will
707 // adjust the DB index because we substituting into a binder (it
708 // tries to be so smart...) resulting in `for<'x> for<'b>
709 // Bar1<'x,'b>` (we have no syntax for this, so use your
710 // imagination). Basically the 'x will have DB index of 2 and 'b
711 // will have DB index of 1. Not quite what we want. So we apply
712 // the substitution to the *contents* of the trait reference,
713 // rather than the trait reference itself (put another way, the
714 // substitution code expects equal binding levels in the values
715 // from the substitution and the value being substituted into, and
716 // this trick achieves that).
718 // Working through the second example:
719 // trait_ref: for<'x> T: Foo1<'^0.0>; substs: [T, '^0.0]
720 // predicate: for<'b> Self: Bar1<'a, '^0.0>; substs: [Self, 'a, '^0.0]
721 // We want to end up with:
722 // for<'x, 'b> T: Bar1<'^0.0, '^0.1>
724 // 1) We must shift all bound vars in predicate by the length
725 // of trait ref's bound vars. So, we would end up with predicate like
726 // Self: Bar1<'a, '^0.1>
727 // 2) We can then apply the trait substs to this, ending up with
728 // T: Bar1<'^0.0, '^0.1>
729 // 3) Finally, to create the final bound vars, we concatenate the bound
730 // vars of the trait ref with those of the predicate:
732 let bound_pred = self.kind();
733 let pred_bound_vars = bound_pred.bound_vars();
734 let trait_bound_vars = trait_ref.bound_vars();
735 // 1) Self: Bar1<'a, '^0.0> -> Self: Bar1<'a, '^0.1>
737 tcx.shift_bound_var_indices(trait_bound_vars.len(), bound_pred.skip_binder());
738 // 2) Self: Bar1<'a, '^0.1> -> T: Bar1<'^0.0, '^0.1>
739 let new = shifted_pred.subst(tcx, trait_ref.skip_binder().substs);
740 // 3) ['x] + ['b] -> ['x, 'b]
742 tcx.mk_bound_variable_kinds(trait_bound_vars.iter().chain(pred_bound_vars));
743 tcx.reuse_or_mk_predicate(self, ty::Binder::bind_with_vars(new, bound_vars))
747 #[derive(Clone, Copy, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
748 #[derive(HashStable, TypeFoldable)]
749 pub struct TraitPredicate<'tcx> {
750 pub trait_ref: TraitRef<'tcx>,
752 pub constness: BoundConstness,
754 pub polarity: ImplPolarity,
757 pub type PolyTraitPredicate<'tcx> = ty::Binder<'tcx, TraitPredicate<'tcx>>;
759 impl<'tcx> TraitPredicate<'tcx> {
760 pub fn remap_constness(&mut self, tcx: TyCtxt<'tcx>, param_env: &mut ParamEnv<'tcx>) {
761 if unlikely!(Some(self.trait_ref.def_id) == tcx.lang_items().drop_trait()) {
762 // remap without changing constness of this predicate.
763 // this is because `T: ~const Drop` has a different meaning to `T: Drop`
764 param_env.remap_constness_with(self.constness)
766 *param_env = param_env.with_constness(self.constness.and(param_env.constness()))
770 /// Remap the constness of this predicate before emitting it for diagnostics.
771 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
772 // this is different to `remap_constness` that callees want to print this predicate
773 // in case of selection errors. `T: ~const Drop` bounds cannot end up here when the
774 // param_env is not const because we it is always satisfied in non-const contexts.
775 if let hir::Constness::NotConst = param_env.constness() {
776 self.constness = ty::BoundConstness::NotConst;
780 pub fn def_id(self) -> DefId {
781 self.trait_ref.def_id
784 pub fn self_ty(self) -> Ty<'tcx> {
785 self.trait_ref.self_ty()
789 pub fn is_const_if_const(self) -> bool {
790 self.constness == BoundConstness::ConstIfConst
794 impl<'tcx> PolyTraitPredicate<'tcx> {
795 pub fn def_id(self) -> DefId {
796 // Ok to skip binder since trait `DefId` does not care about regions.
797 self.skip_binder().def_id()
800 pub fn self_ty(self) -> ty::Binder<'tcx, Ty<'tcx>> {
801 self.map_bound(|trait_ref| trait_ref.self_ty())
804 /// Remap the constness of this predicate before emitting it for diagnostics.
805 pub fn remap_constness_diag(&mut self, param_env: ParamEnv<'tcx>) {
806 *self = self.map_bound(|mut p| {
807 p.remap_constness_diag(param_env);
813 pub fn is_const_if_const(self) -> bool {
814 self.skip_binder().is_const_if_const()
818 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, Debug, TyEncodable, TyDecodable)]
819 #[derive(HashStable, TypeFoldable)]
820 pub struct OutlivesPredicate<A, B>(pub A, pub B); // `A: B`
821 pub type RegionOutlivesPredicate<'tcx> = OutlivesPredicate<ty::Region<'tcx>, ty::Region<'tcx>>;
822 pub type TypeOutlivesPredicate<'tcx> = OutlivesPredicate<Ty<'tcx>, ty::Region<'tcx>>;
823 pub type PolyRegionOutlivesPredicate<'tcx> = ty::Binder<'tcx, RegionOutlivesPredicate<'tcx>>;
824 pub type PolyTypeOutlivesPredicate<'tcx> = ty::Binder<'tcx, TypeOutlivesPredicate<'tcx>>;
826 /// Encodes that `a` must be a subtype of `b`. The `a_is_expected` flag indicates
827 /// whether the `a` type is the type that we should label as "expected" when
828 /// presenting user diagnostics.
829 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
830 #[derive(HashStable, TypeFoldable)]
831 pub struct SubtypePredicate<'tcx> {
832 pub a_is_expected: bool,
836 pub type PolySubtypePredicate<'tcx> = ty::Binder<'tcx, SubtypePredicate<'tcx>>;
838 /// Encodes that we have to coerce *from* the `a` type to the `b` type.
839 #[derive(Clone, Copy, PartialEq, Eq, Hash, Debug, TyEncodable, TyDecodable)]
840 #[derive(HashStable, TypeFoldable)]
841 pub struct CoercePredicate<'tcx> {
845 pub type PolyCoercePredicate<'tcx> = ty::Binder<'tcx, CoercePredicate<'tcx>>;
847 #[derive(Debug, Copy, Clone, PartialEq, Eq, Hash, PartialOrd, Ord, TyEncodable, TyDecodable)]
848 #[derive(HashStable, TypeFoldable)]
849 pub enum Term<'tcx> {
851 Const(&'tcx Const<'tcx>),
854 impl<'tcx> From<Ty<'tcx>> for Term<'tcx> {
855 fn from(ty: Ty<'tcx>) -> Self {
860 impl<'tcx> From<&'tcx Const<'tcx>> for Term<'tcx> {
861 fn from(c: &'tcx Const<'tcx>) -> Self {
866 impl<'tcx> Term<'tcx> {
867 pub fn ty(&self) -> Option<Ty<'tcx>> {
868 if let Term::Ty(ty) = self { Some(ty) } else { None }
872 /// This kind of predicate has no *direct* correspondent in the
873 /// syntax, but it roughly corresponds to the syntactic forms:
875 /// 1. `T: TraitRef<..., Item = Type>`
876 /// 2. `<T as TraitRef<...>>::Item == Type` (NYI)
878 /// In particular, form #1 is "desugared" to the combination of a
879 /// normal trait predicate (`T: TraitRef<...>`) and one of these
880 /// predicates. Form #2 is a broader form in that it also permits
881 /// equality between arbitrary types. Processing an instance of
882 /// Form #2 eventually yields one of these `ProjectionPredicate`
883 /// instances to normalize the LHS.
884 #[derive(Copy, Clone, PartialEq, Eq, Hash, TyEncodable, TyDecodable)]
885 #[derive(HashStable, TypeFoldable)]
886 pub struct ProjectionPredicate<'tcx> {
887 pub projection_ty: ProjectionTy<'tcx>,
888 pub term: Term<'tcx>,
891 pub type PolyProjectionPredicate<'tcx> = Binder<'tcx, ProjectionPredicate<'tcx>>;
893 impl<'tcx> PolyProjectionPredicate<'tcx> {
894 /// Returns the `DefId` of the trait of the associated item being projected.
896 pub fn trait_def_id(&self, tcx: TyCtxt<'tcx>) -> DefId {
897 self.skip_binder().projection_ty.trait_def_id(tcx)
900 /// Get the [PolyTraitRef] required for this projection to be well formed.
901 /// Note that for generic associated types the predicates of the associated
902 /// type also need to be checked.
904 pub fn required_poly_trait_ref(&self, tcx: TyCtxt<'tcx>) -> PolyTraitRef<'tcx> {
905 // Note: unlike with `TraitRef::to_poly_trait_ref()`,
906 // `self.0.trait_ref` is permitted to have escaping regions.
907 // This is because here `self` has a `Binder` and so does our
908 // return value, so we are preserving the number of binding
910 self.map_bound(|predicate| predicate.projection_ty.trait_ref(tcx))
913 pub fn term(&self) -> Binder<'tcx, Term<'tcx>> {
914 self.map_bound(|predicate| predicate.term)
917 /// The `DefId` of the `TraitItem` for the associated type.
919 /// Note that this is not the `DefId` of the `TraitRef` containing this
920 /// associated type, which is in `tcx.associated_item(projection_def_id()).container`.
921 pub fn projection_def_id(&self) -> DefId {
922 // Ok to skip binder since trait `DefId` does not care about regions.
923 self.skip_binder().projection_ty.item_def_id
927 pub trait ToPolyTraitRef<'tcx> {
928 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx>;
931 impl<'tcx> ToPolyTraitRef<'tcx> for PolyTraitPredicate<'tcx> {
932 fn to_poly_trait_ref(&self) -> PolyTraitRef<'tcx> {
933 self.map_bound_ref(|trait_pred| trait_pred.trait_ref)
937 pub trait ToPredicate<'tcx> {
938 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx>;
941 impl<'tcx> ToPredicate<'tcx> for Binder<'tcx, PredicateKind<'tcx>> {
943 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
944 tcx.mk_predicate(self)
948 impl<'tcx> ToPredicate<'tcx> for PolyTraitPredicate<'tcx> {
949 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
950 self.map_bound(PredicateKind::Trait).to_predicate(tcx)
954 impl<'tcx> ToPredicate<'tcx> for PolyRegionOutlivesPredicate<'tcx> {
955 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
956 self.map_bound(PredicateKind::RegionOutlives).to_predicate(tcx)
960 impl<'tcx> ToPredicate<'tcx> for PolyTypeOutlivesPredicate<'tcx> {
961 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
962 self.map_bound(PredicateKind::TypeOutlives).to_predicate(tcx)
966 impl<'tcx> ToPredicate<'tcx> for PolyProjectionPredicate<'tcx> {
967 fn to_predicate(self, tcx: TyCtxt<'tcx>) -> Predicate<'tcx> {
968 self.map_bound(PredicateKind::Projection).to_predicate(tcx)
972 impl<'tcx> Predicate<'tcx> {
973 pub fn to_opt_poly_trait_pred(self) -> Option<PolyTraitPredicate<'tcx>> {
974 let predicate = self.kind();
975 match predicate.skip_binder() {
976 PredicateKind::Trait(t) => Some(predicate.rebind(t)),
977 PredicateKind::Projection(..)
978 | PredicateKind::Subtype(..)
979 | PredicateKind::Coerce(..)
980 | PredicateKind::RegionOutlives(..)
981 | PredicateKind::WellFormed(..)
982 | PredicateKind::ObjectSafe(..)
983 | PredicateKind::ClosureKind(..)
984 | PredicateKind::TypeOutlives(..)
985 | PredicateKind::ConstEvaluatable(..)
986 | PredicateKind::ConstEquate(..)
987 | PredicateKind::TypeWellFormedFromEnv(..) => None,
991 pub fn to_opt_type_outlives(self) -> Option<PolyTypeOutlivesPredicate<'tcx>> {
992 let predicate = self.kind();
993 match predicate.skip_binder() {
994 PredicateKind::TypeOutlives(data) => Some(predicate.rebind(data)),
995 PredicateKind::Trait(..)
996 | PredicateKind::Projection(..)
997 | PredicateKind::Subtype(..)
998 | PredicateKind::Coerce(..)
999 | PredicateKind::RegionOutlives(..)
1000 | PredicateKind::WellFormed(..)
1001 | PredicateKind::ObjectSafe(..)
1002 | PredicateKind::ClosureKind(..)
1003 | PredicateKind::ConstEvaluatable(..)
1004 | PredicateKind::ConstEquate(..)
1005 | PredicateKind::TypeWellFormedFromEnv(..) => None,
1010 /// Represents the bounds declared on a particular set of type
1011 /// parameters. Should eventually be generalized into a flag list of
1012 /// where-clauses. You can obtain an `InstantiatedPredicates` list from a
1013 /// `GenericPredicates` by using the `instantiate` method. Note that this method
1014 /// reflects an important semantic invariant of `InstantiatedPredicates`: while
1015 /// the `GenericPredicates` are expressed in terms of the bound type
1016 /// parameters of the impl/trait/whatever, an `InstantiatedPredicates` instance
1017 /// represented a set of bounds for some particular instantiation,
1018 /// meaning that the generic parameters have been substituted with
1023 /// struct Foo<T, U: Bar<T>> { ... }
1025 /// Here, the `GenericPredicates` for `Foo` would contain a list of bounds like
1026 /// `[[], [U:Bar<T>]]`. Now if there were some particular reference
1027 /// like `Foo<isize,usize>`, then the `InstantiatedPredicates` would be `[[],
1028 /// [usize:Bar<isize>]]`.
1029 #[derive(Clone, Debug, TypeFoldable)]
1030 pub struct InstantiatedPredicates<'tcx> {
1031 pub predicates: Vec<Predicate<'tcx>>,
1032 pub spans: Vec<Span>,
1035 impl<'tcx> InstantiatedPredicates<'tcx> {
1036 pub fn empty() -> InstantiatedPredicates<'tcx> {
1037 InstantiatedPredicates { predicates: vec![], spans: vec![] }
1040 pub fn is_empty(&self) -> bool {
1041 self.predicates.is_empty()
1045 #[derive(Copy, Clone, Debug, PartialEq, Eq, HashStable, TyEncodable, TyDecodable, TypeFoldable)]
1046 pub struct OpaqueTypeKey<'tcx> {
1048 pub substs: SubstsRef<'tcx>,
1051 rustc_index::newtype_index! {
1052 /// "Universes" are used during type- and trait-checking in the
1053 /// presence of `for<..>` binders to control what sets of names are
1054 /// visible. Universes are arranged into a tree: the root universe
1055 /// contains names that are always visible. Each child then adds a new
1056 /// set of names that are visible, in addition to those of its parent.
1057 /// We say that the child universe "extends" the parent universe with
1060 /// To make this more concrete, consider this program:
1064 /// fn bar<T>(x: T) {
1065 /// let y: for<'a> fn(&'a u8, Foo) = ...;
1069 /// The struct name `Foo` is in the root universe U0. But the type
1070 /// parameter `T`, introduced on `bar`, is in an extended universe U1
1071 /// -- i.e., within `bar`, we can name both `T` and `Foo`, but outside
1072 /// of `bar`, we cannot name `T`. Then, within the type of `y`, the
1073 /// region `'a` is in a universe U2 that extends U1, because we can
1074 /// name it inside the fn type but not outside.
1076 /// Universes are used to do type- and trait-checking around these
1077 /// "forall" binders (also called **universal quantification**). The
1078 /// idea is that when, in the body of `bar`, we refer to `T` as a
1079 /// type, we aren't referring to any type in particular, but rather a
1080 /// kind of "fresh" type that is distinct from all other types we have
1081 /// actually declared. This is called a **placeholder** type, and we
1082 /// use universes to talk about this. In other words, a type name in
1083 /// universe 0 always corresponds to some "ground" type that the user
1084 /// declared, but a type name in a non-zero universe is a placeholder
1085 /// type -- an idealized representative of "types in general" that we
1086 /// use for checking generic functions.
1087 pub struct UniverseIndex {
1089 DEBUG_FORMAT = "U{}",
1093 impl UniverseIndex {
1094 pub const ROOT: UniverseIndex = UniverseIndex::from_u32(0);
1096 /// Returns the "next" universe index in order -- this new index
1097 /// is considered to extend all previous universes. This
1098 /// corresponds to entering a `forall` quantifier. So, for
1099 /// example, suppose we have this type in universe `U`:
1102 /// for<'a> fn(&'a u32)
1105 /// Once we "enter" into this `for<'a>` quantifier, we are in a
1106 /// new universe that extends `U` -- in this new universe, we can
1107 /// name the region `'a`, but that region was not nameable from
1108 /// `U` because it was not in scope there.
1109 pub fn next_universe(self) -> UniverseIndex {
1110 UniverseIndex::from_u32(self.private.checked_add(1).unwrap())
1113 /// Returns `true` if `self` can name a name from `other` -- in other words,
1114 /// if the set of names in `self` is a superset of those in
1115 /// `other` (`self >= other`).
1116 pub fn can_name(self, other: UniverseIndex) -> bool {
1117 self.private >= other.private
1120 /// Returns `true` if `self` cannot name some names from `other` -- in other
1121 /// words, if the set of names in `self` is a strict subset of
1122 /// those in `other` (`self < other`).
1123 pub fn cannot_name(self, other: UniverseIndex) -> bool {
1124 self.private < other.private
1128 /// The "placeholder index" fully defines a placeholder region, type, or const. Placeholders are
1129 /// identified by both a universe, as well as a name residing within that universe. Distinct bound
1130 /// regions/types/consts within the same universe simply have an unknown relationship to one
1132 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TyEncodable, TyDecodable, PartialOrd, Ord)]
1133 pub struct Placeholder<T> {
1134 pub universe: UniverseIndex,
1138 impl<'a, T> HashStable<StableHashingContext<'a>> for Placeholder<T>
1140 T: HashStable<StableHashingContext<'a>>,
1142 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1143 self.universe.hash_stable(hcx, hasher);
1144 self.name.hash_stable(hcx, hasher);
1148 pub type PlaceholderRegion = Placeholder<BoundRegionKind>;
1150 pub type PlaceholderType = Placeholder<BoundVar>;
1152 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, HashStable)]
1153 #[derive(TyEncodable, TyDecodable, PartialOrd, Ord)]
1154 pub struct BoundConst<'tcx> {
1159 pub type PlaceholderConst<'tcx> = Placeholder<BoundConst<'tcx>>;
1161 /// A `DefId` which, in case it is a const argument, is potentially bundled with
1162 /// the `DefId` of the generic parameter it instantiates.
1164 /// This is used to avoid calls to `type_of` for const arguments during typeck
1165 /// which cause cycle errors.
1170 /// fn foo<const N: usize>(&self) -> [u8; N] { [0; N] }
1171 /// // ^ const parameter
1175 /// fn foo<const M: u8>(&self) -> usize { 42 }
1176 /// // ^ const parameter
1181 /// let _b = a.foo::<{ 3 + 7 }>();
1182 /// // ^^^^^^^^^ const argument
1186 /// Let's look at the call `a.foo::<{ 3 + 7 }>()` here. We do not know
1187 /// which `foo` is used until we know the type of `a`.
1189 /// We only know the type of `a` once we are inside of `typeck(main)`.
1190 /// We also end up normalizing the type of `_b` during `typeck(main)` which
1191 /// requires us to evaluate the const argument.
1193 /// To evaluate that const argument we need to know its type,
1194 /// which we would get using `type_of(const_arg)`. This requires us to
1195 /// resolve `foo` as it can be either `usize` or `u8` in this example.
1196 /// However, resolving `foo` once again requires `typeck(main)` to get the type of `a`,
1197 /// which results in a cycle.
1199 /// In short we must not call `type_of(const_arg)` during `typeck(main)`.
1201 /// When first creating the `ty::Const` of the const argument inside of `typeck` we have
1202 /// already resolved `foo` so we know which const parameter this argument instantiates.
1203 /// This means that we also know the expected result of `type_of(const_arg)` even if we
1204 /// aren't allowed to call that query: it is equal to `type_of(const_param)` which is
1205 /// trivial to compute.
1207 /// If we now want to use that constant in a place which potentionally needs its type
1208 /// we also pass the type of its `const_param`. This is the point of `WithOptConstParam`,
1209 /// except that instead of a `Ty` we bundle the `DefId` of the const parameter.
1210 /// Meaning that we need to use `type_of(const_param_did)` if `const_param_did` is `Some`
1211 /// to get the type of `did`.
1212 #[derive(Copy, Clone, Debug, TypeFoldable, Lift, TyEncodable, TyDecodable)]
1213 #[derive(PartialEq, Eq, PartialOrd, Ord)]
1214 #[derive(Hash, HashStable)]
1215 pub struct WithOptConstParam<T> {
1217 /// The `DefId` of the corresponding generic parameter in case `did` is
1218 /// a const argument.
1220 /// Note that even if `did` is a const argument, this may still be `None`.
1221 /// All queries taking `WithOptConstParam` start by calling `tcx.opt_const_param_of(def.did)`
1222 /// to potentially update `param_did` in the case it is `None`.
1223 pub const_param_did: Option<DefId>,
1226 impl<T> WithOptConstParam<T> {
1227 /// Creates a new `WithOptConstParam` setting `const_param_did` to `None`.
1229 pub fn unknown(did: T) -> WithOptConstParam<T> {
1230 WithOptConstParam { did, const_param_did: None }
1234 impl WithOptConstParam<LocalDefId> {
1235 /// Returns `Some((did, param_did))` if `def_id` is a const argument,
1236 /// `None` otherwise.
1238 pub fn try_lookup(did: LocalDefId, tcx: TyCtxt<'_>) -> Option<(LocalDefId, DefId)> {
1239 tcx.opt_const_param_of(did).map(|param_did| (did, param_did))
1242 /// In case `self` is unknown but `self.did` is a const argument, this returns
1243 /// a `WithOptConstParam` with the correct `const_param_did`.
1245 pub fn try_upgrade(self, tcx: TyCtxt<'_>) -> Option<WithOptConstParam<LocalDefId>> {
1246 if self.const_param_did.is_none() {
1247 if let const_param_did @ Some(_) = tcx.opt_const_param_of(self.did) {
1248 return Some(WithOptConstParam { did: self.did, const_param_did });
1255 pub fn to_global(self) -> WithOptConstParam<DefId> {
1256 WithOptConstParam { did: self.did.to_def_id(), const_param_did: self.const_param_did }
1259 pub fn def_id_for_type_of(self) -> DefId {
1260 if let Some(did) = self.const_param_did { did } else { self.did.to_def_id() }
1264 impl WithOptConstParam<DefId> {
1265 pub fn as_local(self) -> Option<WithOptConstParam<LocalDefId>> {
1268 .map(|did| WithOptConstParam { did, const_param_did: self.const_param_did })
1271 pub fn as_const_arg(self) -> Option<(LocalDefId, DefId)> {
1272 if let Some(param_did) = self.const_param_did {
1273 if let Some(did) = self.did.as_local() {
1274 return Some((did, param_did));
1281 pub fn is_local(self) -> bool {
1285 pub fn def_id_for_type_of(self) -> DefId {
1286 self.const_param_did.unwrap_or(self.did)
1290 /// When type checking, we use the `ParamEnv` to track
1291 /// details about the set of where-clauses that are in scope at this
1292 /// particular point.
1293 #[derive(Copy, Clone, Hash, PartialEq, Eq)]
1294 pub struct ParamEnv<'tcx> {
1295 /// This packs both caller bounds and the reveal enum into one pointer.
1297 /// Caller bounds are `Obligation`s that the caller must satisfy. This is
1298 /// basically the set of bounds on the in-scope type parameters, translated
1299 /// into `Obligation`s, and elaborated and normalized.
1301 /// Use the `caller_bounds()` method to access.
1303 /// Typically, this is `Reveal::UserFacing`, but during codegen we
1304 /// want `Reveal::All`.
1306 /// Note: This is packed, use the reveal() method to access it.
1307 packed: CopyTaggedPtr<&'tcx List<Predicate<'tcx>>, ParamTag, true>,
1310 #[derive(Copy, Clone)]
1312 reveal: traits::Reveal,
1313 constness: hir::Constness,
1316 unsafe impl rustc_data_structures::tagged_ptr::Tag for ParamTag {
1317 const BITS: usize = 2;
1319 fn into_usize(self) -> usize {
1321 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst } => 0,
1322 Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst } => 1,
1323 Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const } => 2,
1324 Self { reveal: traits::Reveal::All, constness: hir::Constness::Const } => 3,
1328 unsafe fn from_usize(ptr: usize) -> Self {
1330 0 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::NotConst },
1331 1 => Self { reveal: traits::Reveal::All, constness: hir::Constness::NotConst },
1332 2 => Self { reveal: traits::Reveal::UserFacing, constness: hir::Constness::Const },
1333 3 => Self { reveal: traits::Reveal::All, constness: hir::Constness::Const },
1334 _ => std::hint::unreachable_unchecked(),
1339 impl<'tcx> fmt::Debug for ParamEnv<'tcx> {
1340 fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
1341 f.debug_struct("ParamEnv")
1342 .field("caller_bounds", &self.caller_bounds())
1343 .field("reveal", &self.reveal())
1344 .field("constness", &self.constness())
1349 impl<'a, 'tcx> HashStable<StableHashingContext<'a>> for ParamEnv<'tcx> {
1350 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1351 self.caller_bounds().hash_stable(hcx, hasher);
1352 self.reveal().hash_stable(hcx, hasher);
1353 self.constness().hash_stable(hcx, hasher);
1357 impl<'tcx> TypeFoldable<'tcx> for ParamEnv<'tcx> {
1358 fn try_super_fold_with<F: ty::fold::FallibleTypeFolder<'tcx>>(
1361 ) -> Result<Self, F::Error> {
1363 self.caller_bounds().try_fold_with(folder)?,
1364 self.reveal().try_fold_with(folder)?,
1365 self.constness().try_fold_with(folder)?,
1369 fn super_visit_with<V: TypeVisitor<'tcx>>(&self, visitor: &mut V) -> ControlFlow<V::BreakTy> {
1370 self.caller_bounds().visit_with(visitor)?;
1371 self.reveal().visit_with(visitor)?;
1372 self.constness().visit_with(visitor)
1376 impl<'tcx> ParamEnv<'tcx> {
1377 /// Construct a trait environment suitable for contexts where
1378 /// there are no where-clauses in scope. Hidden types (like `impl
1379 /// Trait`) are left hidden, so this is suitable for ordinary
1382 pub fn empty() -> Self {
1383 Self::new(List::empty(), Reveal::UserFacing, hir::Constness::NotConst)
1387 pub fn caller_bounds(self) -> &'tcx List<Predicate<'tcx>> {
1388 self.packed.pointer()
1392 pub fn reveal(self) -> traits::Reveal {
1393 self.packed.tag().reveal
1397 pub fn constness(self) -> hir::Constness {
1398 self.packed.tag().constness
1402 pub fn is_const(self) -> bool {
1403 self.packed.tag().constness == hir::Constness::Const
1406 /// Construct a trait environment with no where-clauses in scope
1407 /// where the values of all `impl Trait` and other hidden types
1408 /// are revealed. This is suitable for monomorphized, post-typeck
1409 /// environments like codegen or doing optimizations.
1411 /// N.B., if you want to have predicates in scope, use `ParamEnv::new`,
1412 /// or invoke `param_env.with_reveal_all()`.
1414 pub fn reveal_all() -> Self {
1415 Self::new(List::empty(), Reveal::All, hir::Constness::NotConst)
1418 /// Construct a trait environment with the given set of predicates.
1421 caller_bounds: &'tcx List<Predicate<'tcx>>,
1423 constness: hir::Constness,
1425 ty::ParamEnv { packed: CopyTaggedPtr::new(caller_bounds, ParamTag { reveal, constness }) }
1428 pub fn with_user_facing(mut self) -> Self {
1429 self.packed.set_tag(ParamTag { reveal: Reveal::UserFacing, ..self.packed.tag() });
1434 pub fn with_constness(mut self, constness: hir::Constness) -> Self {
1435 self.packed.set_tag(ParamTag { constness, ..self.packed.tag() });
1440 pub fn with_const(mut self) -> Self {
1441 self.packed.set_tag(ParamTag { constness: hir::Constness::Const, ..self.packed.tag() });
1446 pub fn without_const(mut self) -> Self {
1447 self.packed.set_tag(ParamTag { constness: hir::Constness::NotConst, ..self.packed.tag() });
1452 pub fn remap_constness_with(&mut self, mut constness: ty::BoundConstness) {
1453 *self = self.with_constness(constness.and(self.constness()))
1456 /// Returns a new parameter environment with the same clauses, but
1457 /// which "reveals" the true results of projections in all cases
1458 /// (even for associated types that are specializable). This is
1459 /// the desired behavior during codegen and certain other special
1460 /// contexts; normally though we want to use `Reveal::UserFacing`,
1461 /// which is the default.
1462 /// All opaque types in the caller_bounds of the `ParamEnv`
1463 /// will be normalized to their underlying types.
1464 /// See PR #65989 and issue #65918 for more details
1465 pub fn with_reveal_all_normalized(self, tcx: TyCtxt<'tcx>) -> Self {
1466 if self.packed.tag().reveal == traits::Reveal::All {
1471 tcx.normalize_opaque_types(self.caller_bounds()),
1477 /// Returns this same environment but with no caller bounds.
1479 pub fn without_caller_bounds(self) -> Self {
1480 Self::new(List::empty(), self.reveal(), self.constness())
1483 /// Creates a suitable environment in which to perform trait
1484 /// queries on the given value. When type-checking, this is simply
1485 /// the pair of the environment plus value. But when reveal is set to
1486 /// All, then if `value` does not reference any type parameters, we will
1487 /// pair it with the empty environment. This improves caching and is generally
1490 /// N.B., we preserve the environment when type-checking because it
1491 /// is possible for the user to have wacky where-clauses like
1492 /// `where Box<u32>: Copy`, which are clearly never
1493 /// satisfiable. We generally want to behave as if they were true,
1494 /// although the surrounding function is never reachable.
1495 pub fn and<T: TypeFoldable<'tcx>>(self, value: T) -> ParamEnvAnd<'tcx, T> {
1496 match self.reveal() {
1497 Reveal::UserFacing => ParamEnvAnd { param_env: self, value },
1500 if value.is_global() {
1501 ParamEnvAnd { param_env: self.without_caller_bounds(), value }
1503 ParamEnvAnd { param_env: self, value }
1510 // FIXME(ecstaticmorse): Audit all occurrences of `without_const().to_predicate(tcx)` to ensure that
1511 // the constness of trait bounds is being propagated correctly.
1512 impl<'tcx> PolyTraitRef<'tcx> {
1514 pub fn with_constness(self, constness: BoundConstness) -> PolyTraitPredicate<'tcx> {
1515 self.map_bound(|trait_ref| ty::TraitPredicate {
1518 polarity: ty::ImplPolarity::Positive,
1523 pub fn without_const(self) -> PolyTraitPredicate<'tcx> {
1524 self.with_constness(BoundConstness::NotConst)
1528 #[derive(Copy, Clone, Debug, PartialEq, Eq, Hash, TypeFoldable)]
1529 pub struct ParamEnvAnd<'tcx, T> {
1530 pub param_env: ParamEnv<'tcx>,
1534 impl<'tcx, T> ParamEnvAnd<'tcx, T> {
1535 pub fn into_parts(self) -> (ParamEnv<'tcx>, T) {
1536 (self.param_env, self.value)
1540 pub fn without_const(mut self) -> Self {
1541 self.param_env = self.param_env.without_const();
1546 impl<'a, 'tcx, T> HashStable<StableHashingContext<'a>> for ParamEnvAnd<'tcx, T>
1548 T: HashStable<StableHashingContext<'a>>,
1550 fn hash_stable(&self, hcx: &mut StableHashingContext<'a>, hasher: &mut StableHasher) {
1551 let ParamEnvAnd { ref param_env, ref value } = *self;
1553 param_env.hash_stable(hcx, hasher);
1554 value.hash_stable(hcx, hasher);
1558 #[derive(Copy, Clone, Debug, HashStable)]
1559 pub struct Destructor {
1560 /// The `DefId` of the destructor method
1562 /// The constness of the destructor method
1563 pub constness: hir::Constness,
1567 #[derive(HashStable, TyEncodable, TyDecodable)]
1568 pub struct VariantFlags: u32 {
1569 const NO_VARIANT_FLAGS = 0;
1570 /// Indicates whether the field list of this variant is `#[non_exhaustive]`.
1571 const IS_FIELD_LIST_NON_EXHAUSTIVE = 1 << 0;
1572 /// Indicates whether this variant was obtained as part of recovering from
1573 /// a syntactic error. May be incomplete or bogus.
1574 const IS_RECOVERED = 1 << 1;
1578 /// Definition of a variant -- a struct's fields or an enum variant.
1579 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1580 pub struct VariantDef {
1581 /// `DefId` that identifies the variant itself.
1582 /// If this variant belongs to a struct or union, then this is a copy of its `DefId`.
1584 /// `DefId` that identifies the variant's constructor.
1585 /// If this variant is a struct variant, then this is `None`.
1586 pub ctor_def_id: Option<DefId>,
1587 /// Variant or struct name.
1589 /// Discriminant of this variant.
1590 pub discr: VariantDiscr,
1591 /// Fields of this variant.
1592 pub fields: Vec<FieldDef>,
1593 /// Type of constructor of variant.
1594 pub ctor_kind: CtorKind,
1595 /// Flags of the variant (e.g. is field list non-exhaustive)?
1596 flags: VariantFlags,
1600 /// Creates a new `VariantDef`.
1602 /// `variant_did` is the `DefId` that identifies the enum variant (if this `VariantDef`
1603 /// represents an enum variant).
1605 /// `ctor_did` is the `DefId` that identifies the constructor of unit or
1606 /// tuple-variants/structs. If this is a `struct`-variant then this should be `None`.
1608 /// `parent_did` is the `DefId` of the `AdtDef` representing the enum or struct that
1609 /// owns this variant. It is used for checking if a struct has `#[non_exhaustive]` w/out having
1610 /// to go through the redirect of checking the ctor's attributes - but compiling a small crate
1611 /// requires loading the `AdtDef`s for all the structs in the universe (e.g., coherence for any
1612 /// built-in trait), and we do not want to load attributes twice.
1614 /// If someone speeds up attribute loading to not be a performance concern, they can
1615 /// remove this hack and use the constructor `DefId` everywhere.
1618 variant_did: Option<DefId>,
1619 ctor_def_id: Option<DefId>,
1620 discr: VariantDiscr,
1621 fields: Vec<FieldDef>,
1622 ctor_kind: CtorKind,
1626 is_field_list_non_exhaustive: bool,
1629 "VariantDef::new(name = {:?}, variant_did = {:?}, ctor_def_id = {:?}, discr = {:?},
1630 fields = {:?}, ctor_kind = {:?}, adt_kind = {:?}, parent_did = {:?})",
1631 name, variant_did, ctor_def_id, discr, fields, ctor_kind, adt_kind, parent_did,
1634 let mut flags = VariantFlags::NO_VARIANT_FLAGS;
1635 if is_field_list_non_exhaustive {
1636 flags |= VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE;
1640 flags |= VariantFlags::IS_RECOVERED;
1644 def_id: variant_did.unwrap_or(parent_did),
1654 /// Is this field list non-exhaustive?
1656 pub fn is_field_list_non_exhaustive(&self) -> bool {
1657 self.flags.intersects(VariantFlags::IS_FIELD_LIST_NON_EXHAUSTIVE)
1660 /// Was this variant obtained as part of recovering from a syntactic error?
1662 pub fn is_recovered(&self) -> bool {
1663 self.flags.intersects(VariantFlags::IS_RECOVERED)
1666 /// Computes the `Ident` of this variant by looking up the `Span`
1667 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1668 Ident::new(self.name, tcx.def_ident_span(self.def_id).unwrap())
1672 #[derive(Copy, Clone, Debug, PartialEq, Eq, TyEncodable, TyDecodable, HashStable)]
1673 pub enum VariantDiscr {
1674 /// Explicit value for this variant, i.e., `X = 123`.
1675 /// The `DefId` corresponds to the embedded constant.
1678 /// The previous variant's discriminant plus one.
1679 /// For efficiency reasons, the distance from the
1680 /// last `Explicit` discriminant is being stored,
1681 /// or `0` for the first variant, if it has none.
1685 #[derive(Debug, HashStable, TyEncodable, TyDecodable)]
1686 pub struct FieldDef {
1689 pub vis: Visibility,
1693 #[derive(TyEncodable, TyDecodable, Default, HashStable)]
1694 pub struct ReprFlags: u8 {
1695 const IS_C = 1 << 0;
1696 const IS_SIMD = 1 << 1;
1697 const IS_TRANSPARENT = 1 << 2;
1698 // Internal only for now. If true, don't reorder fields.
1699 const IS_LINEAR = 1 << 3;
1700 // If true, don't expose any niche to type's context.
1701 const HIDE_NICHE = 1 << 4;
1702 // If true, the type's layout can be randomized using
1703 // the seed stored in `ReprOptions.layout_seed`
1704 const RANDOMIZE_LAYOUT = 1 << 5;
1705 // Any of these flags being set prevent field reordering optimisation.
1706 const IS_UNOPTIMISABLE = ReprFlags::IS_C.bits
1707 | ReprFlags::IS_SIMD.bits
1708 | ReprFlags::IS_LINEAR.bits;
1712 /// Represents the repr options provided by the user,
1713 #[derive(Copy, Clone, Debug, Eq, PartialEq, TyEncodable, TyDecodable, Default, HashStable)]
1714 pub struct ReprOptions {
1715 pub int: Option<attr::IntType>,
1716 pub align: Option<Align>,
1717 pub pack: Option<Align>,
1718 pub flags: ReprFlags,
1719 /// The seed to be used for randomizing a type's layout
1721 /// Note: This could technically be a `[u8; 16]` (a `u128`) which would
1722 /// be the "most accurate" hash as it'd encompass the item and crate
1723 /// hash without loss, but it does pay the price of being larger.
1724 /// Everything's a tradeoff, a `u64` seed should be sufficient for our
1725 /// purposes (primarily `-Z randomize-layout`)
1726 pub field_shuffle_seed: u64,
1730 pub fn new(tcx: TyCtxt<'_>, did: DefId) -> ReprOptions {
1731 let mut flags = ReprFlags::empty();
1732 let mut size = None;
1733 let mut max_align: Option<Align> = None;
1734 let mut min_pack: Option<Align> = None;
1736 // Generate a deterministically-derived seed from the item's path hash
1737 // to allow for cross-crate compilation to actually work
1738 let mut field_shuffle_seed = tcx.def_path_hash(did).0.to_smaller_hash();
1740 // If the user defined a custom seed for layout randomization, xor the item's
1741 // path hash with the user defined seed, this will allowing determinism while
1742 // still allowing users to further randomize layout generation for e.g. fuzzing
1743 if let Some(user_seed) = tcx.sess.opts.debugging_opts.layout_seed {
1744 field_shuffle_seed ^= user_seed;
1747 for attr in tcx.get_attrs(did).iter() {
1748 for r in attr::find_repr_attrs(&tcx.sess, attr) {
1749 flags.insert(match r {
1750 attr::ReprC => ReprFlags::IS_C,
1751 attr::ReprPacked(pack) => {
1752 let pack = Align::from_bytes(pack as u64).unwrap();
1753 min_pack = Some(if let Some(min_pack) = min_pack {
1760 attr::ReprTransparent => ReprFlags::IS_TRANSPARENT,
1761 attr::ReprNoNiche => ReprFlags::HIDE_NICHE,
1762 attr::ReprSimd => ReprFlags::IS_SIMD,
1763 attr::ReprInt(i) => {
1767 attr::ReprAlign(align) => {
1768 max_align = max_align.max(Some(Align::from_bytes(align as u64).unwrap()));
1775 // If `-Z randomize-layout` was enabled for the type definition then we can
1776 // consider performing layout randomization
1777 if tcx.sess.opts.debugging_opts.randomize_layout {
1778 flags.insert(ReprFlags::RANDOMIZE_LAYOUT);
1781 // This is here instead of layout because the choice must make it into metadata.
1782 if !tcx.consider_optimizing(|| format!("Reorder fields of {:?}", tcx.def_path_str(did))) {
1783 flags.insert(ReprFlags::IS_LINEAR);
1786 Self { int: size, align: max_align, pack: min_pack, flags, field_shuffle_seed }
1790 pub fn simd(&self) -> bool {
1791 self.flags.contains(ReprFlags::IS_SIMD)
1795 pub fn c(&self) -> bool {
1796 self.flags.contains(ReprFlags::IS_C)
1800 pub fn packed(&self) -> bool {
1805 pub fn transparent(&self) -> bool {
1806 self.flags.contains(ReprFlags::IS_TRANSPARENT)
1810 pub fn linear(&self) -> bool {
1811 self.flags.contains(ReprFlags::IS_LINEAR)
1815 pub fn hide_niche(&self) -> bool {
1816 self.flags.contains(ReprFlags::HIDE_NICHE)
1819 /// Returns the discriminant type, given these `repr` options.
1820 /// This must only be called on enums!
1821 pub fn discr_type(&self) -> attr::IntType {
1822 self.int.unwrap_or(attr::SignedInt(ast::IntTy::Isize))
1825 /// Returns `true` if this `#[repr()]` should inhabit "smart enum
1826 /// layout" optimizations, such as representing `Foo<&T>` as a
1828 pub fn inhibit_enum_layout_opt(&self) -> bool {
1829 self.c() || self.int.is_some()
1832 /// Returns `true` if this `#[repr()]` should inhibit struct field reordering
1833 /// optimizations, such as with `repr(C)`, `repr(packed(1))`, or `repr(<int>)`.
1834 pub fn inhibit_struct_field_reordering_opt(&self) -> bool {
1835 if let Some(pack) = self.pack {
1836 if pack.bytes() == 1 {
1841 self.flags.intersects(ReprFlags::IS_UNOPTIMISABLE) || self.int.is_some()
1844 /// Returns `true` if this type is valid for reordering and `-Z randomize-layout`
1845 /// was enabled for its declaration crate
1846 pub fn can_randomize_type_layout(&self) -> bool {
1847 !self.inhibit_struct_field_reordering_opt()
1848 && self.flags.contains(ReprFlags::RANDOMIZE_LAYOUT)
1851 /// Returns `true` if this `#[repr()]` should inhibit union ABI optimisations.
1852 pub fn inhibit_union_abi_opt(&self) -> bool {
1857 impl<'tcx> FieldDef {
1858 /// Returns the type of this field. The resulting type is not normalized. The `subst` is
1859 /// typically obtained via the second field of [`TyKind::Adt`].
1860 pub fn ty(&self, tcx: TyCtxt<'tcx>, subst: SubstsRef<'tcx>) -> Ty<'tcx> {
1861 tcx.type_of(self.did).subst(tcx, subst)
1864 /// Computes the `Ident` of this variant by looking up the `Span`
1865 pub fn ident(&self, tcx: TyCtxt<'_>) -> Ident {
1866 Ident::new(self.name, tcx.def_ident_span(self.did).unwrap())
1870 pub type Attributes<'tcx> = &'tcx [ast::Attribute];
1872 #[derive(Debug, PartialEq, Eq)]
1873 pub enum ImplOverlapKind {
1874 /// These impls are always allowed to overlap.
1876 /// Whether or not the impl is permitted due to the trait being a `#[marker]` trait
1879 /// These impls are allowed to overlap, but that raises
1880 /// an issue #33140 future-compatibility warning.
1882 /// Some background: in Rust 1.0, the trait-object types `Send + Sync` (today's
1883 /// `dyn Send + Sync`) and `Sync + Send` (now `dyn Sync + Send`) were different.
1885 /// The widely-used version 0.1.0 of the crate `traitobject` had accidentally relied
1886 /// that difference, making what reduces to the following set of impls:
1890 /// impl Trait for dyn Send + Sync {}
1891 /// impl Trait for dyn Sync + Send {}
1894 /// Obviously, once we made these types be identical, that code causes a coherence
1895 /// error and a fairly big headache for us. However, luckily for us, the trait
1896 /// `Trait` used in this case is basically a marker trait, and therefore having
1897 /// overlapping impls for it is sound.
1899 /// To handle this, we basically regard the trait as a marker trait, with an additional
1900 /// future-compatibility warning. To avoid accidentally "stabilizing" this feature,
1901 /// it has the following restrictions:
1903 /// 1. The trait must indeed be a marker-like trait (i.e., no items), and must be
1905 /// 2. The trait-ref of both impls must be equal.
1906 /// 3. The trait-ref of both impls must be a trait object type consisting only of
1908 /// 4. Neither of the impls can have any where-clauses.
1910 /// Once `traitobject` 0.1.0 is no longer an active concern, this hack can be removed.
1914 impl<'tcx> TyCtxt<'tcx> {
1915 pub fn typeck_body(self, body: hir::BodyId) -> &'tcx TypeckResults<'tcx> {
1916 self.typeck(self.hir().body_owner_def_id(body))
1919 pub fn provided_trait_methods(self, id: DefId) -> impl 'tcx + Iterator<Item = &'tcx AssocItem> {
1920 self.associated_items(id)
1921 .in_definition_order()
1922 .filter(|item| item.kind == AssocKind::Fn && item.defaultness.has_value())
1925 fn item_name_from_hir(self, def_id: DefId) -> Option<Ident> {
1926 self.hir().get_if_local(def_id).and_then(|node| node.ident())
1929 fn item_name_from_def_id(self, def_id: DefId) -> Option<Symbol> {
1930 if def_id.index == CRATE_DEF_INDEX {
1931 Some(self.crate_name(def_id.krate))
1933 let def_key = self.def_key(def_id);
1934 match def_key.disambiguated_data.data {
1935 // The name of a constructor is that of its parent.
1936 rustc_hir::definitions::DefPathData::Ctor => self.item_name_from_def_id(DefId {
1937 krate: def_id.krate,
1938 index: def_key.parent.unwrap(),
1940 _ => def_key.disambiguated_data.data.get_opt_name(),
1945 /// Look up the name of an item across crates. This does not look at HIR.
1947 /// When possible, this function should be used for cross-crate lookups over
1948 /// [`opt_item_name`] to avoid invalidating the incremental cache. If you
1949 /// need to handle items without a name, or HIR items that will not be
1950 /// serialized cross-crate, or if you need the span of the item, use
1951 /// [`opt_item_name`] instead.
1953 /// [`opt_item_name`]: Self::opt_item_name
1954 pub fn item_name(self, id: DefId) -> Symbol {
1955 // Look at cross-crate items first to avoid invalidating the incremental cache
1956 // unless we have to.
1957 self.item_name_from_def_id(id).unwrap_or_else(|| {
1958 bug!("item_name: no name for {:?}", self.def_path(id));
1962 /// Look up the name and span of an item or [`Node`].
1964 /// See [`item_name`][Self::item_name] for more information.
1965 pub fn opt_item_name(self, def_id: DefId) -> Option<Ident> {
1966 // Look at the HIR first so the span will be correct if this is a local item.
1967 self.item_name_from_hir(def_id)
1968 .or_else(|| self.item_name_from_def_id(def_id).map(Ident::with_dummy_span))
1971 pub fn opt_associated_item(self, def_id: DefId) -> Option<&'tcx AssocItem> {
1972 if let DefKind::AssocConst | DefKind::AssocFn | DefKind::AssocTy = self.def_kind(def_id) {
1973 Some(self.associated_item(def_id))
1979 pub fn field_index(self, hir_id: hir::HirId, typeck_results: &TypeckResults<'_>) -> usize {
1980 typeck_results.field_indices().get(hir_id).cloned().expect("no index for a field")
1983 pub fn find_field_index(self, ident: Ident, variant: &VariantDef) -> Option<usize> {
1987 .position(|field| self.hygienic_eq(ident, field.ident(self), variant.def_id))
1990 /// Returns `true` if the impls are the same polarity and the trait either
1991 /// has no items or is annotated `#[marker]` and prevents item overrides.
1992 pub fn impls_are_allowed_to_overlap(
1996 ) -> Option<ImplOverlapKind> {
1997 // If either trait impl references an error, they're allowed to overlap,
1998 // as one of them essentially doesn't exist.
1999 if self.impl_trait_ref(def_id1).map_or(false, |tr| tr.references_error())
2000 || self.impl_trait_ref(def_id2).map_or(false, |tr| tr.references_error())
2002 return Some(ImplOverlapKind::Permitted { marker: false });
2005 match (self.impl_polarity(def_id1), self.impl_polarity(def_id2)) {
2006 (ImplPolarity::Reservation, _) | (_, ImplPolarity::Reservation) => {
2007 // `#[rustc_reservation_impl]` impls don't overlap with anything
2009 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (reservations)",
2012 return Some(ImplOverlapKind::Permitted { marker: false });
2014 (ImplPolarity::Positive, ImplPolarity::Negative)
2015 | (ImplPolarity::Negative, ImplPolarity::Positive) => {
2016 // `impl AutoTrait for Type` + `impl !AutoTrait for Type`
2018 "impls_are_allowed_to_overlap({:?}, {:?}) - None (differing polarities)",
2023 (ImplPolarity::Positive, ImplPolarity::Positive)
2024 | (ImplPolarity::Negative, ImplPolarity::Negative) => {}
2027 let is_marker_overlap = {
2028 let is_marker_impl = |def_id: DefId| -> bool {
2029 let trait_ref = self.impl_trait_ref(def_id);
2030 trait_ref.map_or(false, |tr| self.trait_def(tr.def_id).is_marker)
2032 is_marker_impl(def_id1) && is_marker_impl(def_id2)
2035 if is_marker_overlap {
2037 "impls_are_allowed_to_overlap({:?}, {:?}) = Some(Permitted) (marker overlap)",
2040 Some(ImplOverlapKind::Permitted { marker: true })
2042 if let Some(self_ty1) = self.issue33140_self_ty(def_id1) {
2043 if let Some(self_ty2) = self.issue33140_self_ty(def_id2) {
2044 if self_ty1 == self_ty2 {
2046 "impls_are_allowed_to_overlap({:?}, {:?}) - issue #33140 HACK",
2049 return Some(ImplOverlapKind::Issue33140);
2052 "impls_are_allowed_to_overlap({:?}, {:?}) - found {:?} != {:?}",
2053 def_id1, def_id2, self_ty1, self_ty2
2059 debug!("impls_are_allowed_to_overlap({:?}, {:?}) = None", def_id1, def_id2);
2064 /// Returns `ty::VariantDef` if `res` refers to a struct,
2065 /// or variant or their constructors, panics otherwise.
2066 pub fn expect_variant_res(self, res: Res) -> &'tcx VariantDef {
2068 Res::Def(DefKind::Variant, did) => {
2069 let enum_did = self.parent(did).unwrap();
2070 self.adt_def(enum_did).variant_with_id(did)
2072 Res::Def(DefKind::Struct | DefKind::Union, did) => self.adt_def(did).non_enum_variant(),
2073 Res::Def(DefKind::Ctor(CtorOf::Variant, ..), variant_ctor_did) => {
2074 let variant_did = self.parent(variant_ctor_did).unwrap();
2075 let enum_did = self.parent(variant_did).unwrap();
2076 self.adt_def(enum_did).variant_with_ctor_id(variant_ctor_did)
2078 Res::Def(DefKind::Ctor(CtorOf::Struct, ..), ctor_did) => {
2079 let struct_did = self.parent(ctor_did).expect("struct ctor has no parent");
2080 self.adt_def(struct_did).non_enum_variant()
2082 _ => bug!("expect_variant_res used with unexpected res {:?}", res),
2086 /// Returns the possibly-auto-generated MIR of a `(DefId, Subst)` pair.
2087 pub fn instance_mir(self, instance: ty::InstanceDef<'tcx>) -> &'tcx Body<'tcx> {
2089 ty::InstanceDef::Item(def) => match self.def_kind(def.did) {
2092 | DefKind::AssocConst
2094 | DefKind::AnonConst
2095 | DefKind::InlineConst => self.mir_for_ctfe_opt_const_arg(def),
2096 // If the caller wants `mir_for_ctfe` of a function they should not be using
2097 // `instance_mir`, so we'll assume const fn also wants the optimized version.
2099 assert_eq!(def.const_param_did, None);
2100 self.optimized_mir(def.did)
2103 ty::InstanceDef::VtableShim(..)
2104 | ty::InstanceDef::ReifyShim(..)
2105 | ty::InstanceDef::Intrinsic(..)
2106 | ty::InstanceDef::FnPtrShim(..)
2107 | ty::InstanceDef::Virtual(..)
2108 | ty::InstanceDef::ClosureOnceShim { .. }
2109 | ty::InstanceDef::DropGlue(..)
2110 | ty::InstanceDef::CloneShim(..) => self.mir_shims(instance),
2114 /// Gets the attributes of a definition.
2115 pub fn get_attrs(self, did: DefId) -> Attributes<'tcx> {
2116 if let Some(did) = did.as_local() {
2117 self.hir().attrs(self.hir().local_def_id_to_hir_id(did))
2119 self.item_attrs(did)
2123 /// Determines whether an item is annotated with an attribute.
2124 pub fn has_attr(self, did: DefId, attr: Symbol) -> bool {
2125 self.sess.contains_name(&self.get_attrs(did), attr)
2128 /// Determines whether an item is annotated with `doc(hidden)`.
2129 pub fn is_doc_hidden(self, did: DefId) -> bool {
2132 .filter_map(|attr| if attr.has_name(sym::doc) { attr.meta_item_list() } else { None })
2133 .any(|items| items.iter().any(|item| item.has_name(sym::hidden)))
2136 /// Returns `true` if this is an `auto trait`.
2137 pub fn trait_is_auto(self, trait_def_id: DefId) -> bool {
2138 self.trait_def(trait_def_id).has_auto_impl
2141 /// Returns layout of a generator. Layout might be unavailable if the
2142 /// generator is tainted by errors.
2143 pub fn generator_layout(self, def_id: DefId) -> Option<&'tcx GeneratorLayout<'tcx>> {
2144 self.optimized_mir(def_id).generator_layout()
2147 /// Given the `DefId` of an impl, returns the `DefId` of the trait it implements.
2148 /// If it implements no trait, returns `None`.
2149 pub fn trait_id_of_impl(self, def_id: DefId) -> Option<DefId> {
2150 self.impl_trait_ref(def_id).map(|tr| tr.def_id)
2153 /// If the given defid describes a method belonging to an impl, returns the
2154 /// `DefId` of the impl that the method belongs to; otherwise, returns `None`.
2155 pub fn impl_of_method(self, def_id: DefId) -> Option<DefId> {
2156 self.opt_associated_item(def_id).and_then(|trait_item| match trait_item.container {
2157 TraitContainer(_) => None,
2158 ImplContainer(def_id) => Some(def_id),
2162 /// Looks up the span of `impl_did` if the impl is local; otherwise returns `Err`
2163 /// with the name of the crate containing the impl.
2164 pub fn span_of_impl(self, impl_did: DefId) -> Result<Span, Symbol> {
2165 if let Some(impl_did) = impl_did.as_local() {
2166 Ok(self.def_span(impl_did))
2168 Err(self.crate_name(impl_did.krate))
2172 /// Hygienically compares a use-site name (`use_name`) for a field or an associated item with
2173 /// its supposed definition name (`def_name`). The method also needs `DefId` of the supposed
2174 /// definition's parent/scope to perform comparison.
2175 pub fn hygienic_eq(self, use_name: Ident, def_name: Ident, def_parent_def_id: DefId) -> bool {
2176 // We could use `Ident::eq` here, but we deliberately don't. The name
2177 // comparison fails frequently, and we want to avoid the expensive
2178 // `normalize_to_macros_2_0()` calls required for the span comparison whenever possible.
2179 use_name.name == def_name.name
2183 .hygienic_eq(def_name.span.ctxt(), self.expn_that_defined(def_parent_def_id))
2186 pub fn adjust_ident(self, mut ident: Ident, scope: DefId) -> Ident {
2187 ident.span.normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope));
2191 pub fn adjust_ident_and_get_scope(
2196 ) -> (Ident, DefId) {
2199 .normalize_to_macros_2_0_and_adjust(self.expn_that_defined(scope))
2200 .and_then(|actual_expansion| actual_expansion.expn_data().parent_module)
2201 .unwrap_or_else(|| self.parent_module(block).to_def_id());
2205 pub fn is_object_safe(self, key: DefId) -> bool {
2206 self.object_safety_violations(key).is_empty()
2210 /// Yields the parent function's `LocalDefId` if `def_id` is an `impl Trait` definition.
2211 pub fn is_impl_trait_defn(tcx: TyCtxt<'_>, def_id: DefId) -> Option<LocalDefId> {
2212 let def_id = def_id.as_local()?;
2213 if let Node::Item(item) = tcx.hir().get_by_def_id(def_id) {
2214 if let hir::ItemKind::OpaqueTy(ref opaque_ty) = item.kind {
2215 return match opaque_ty.origin {
2216 hir::OpaqueTyOrigin::FnReturn(parent) | hir::OpaqueTyOrigin::AsyncFn(parent) => {
2219 hir::OpaqueTyOrigin::TyAlias => None,
2226 pub fn int_ty(ity: ast::IntTy) -> IntTy {
2228 ast::IntTy::Isize => IntTy::Isize,
2229 ast::IntTy::I8 => IntTy::I8,
2230 ast::IntTy::I16 => IntTy::I16,
2231 ast::IntTy::I32 => IntTy::I32,
2232 ast::IntTy::I64 => IntTy::I64,
2233 ast::IntTy::I128 => IntTy::I128,
2237 pub fn uint_ty(uty: ast::UintTy) -> UintTy {
2239 ast::UintTy::Usize => UintTy::Usize,
2240 ast::UintTy::U8 => UintTy::U8,
2241 ast::UintTy::U16 => UintTy::U16,
2242 ast::UintTy::U32 => UintTy::U32,
2243 ast::UintTy::U64 => UintTy::U64,
2244 ast::UintTy::U128 => UintTy::U128,
2248 pub fn float_ty(fty: ast::FloatTy) -> FloatTy {
2250 ast::FloatTy::F32 => FloatTy::F32,
2251 ast::FloatTy::F64 => FloatTy::F64,
2255 pub fn ast_int_ty(ity: IntTy) -> ast::IntTy {
2257 IntTy::Isize => ast::IntTy::Isize,
2258 IntTy::I8 => ast::IntTy::I8,
2259 IntTy::I16 => ast::IntTy::I16,
2260 IntTy::I32 => ast::IntTy::I32,
2261 IntTy::I64 => ast::IntTy::I64,
2262 IntTy::I128 => ast::IntTy::I128,
2266 pub fn ast_uint_ty(uty: UintTy) -> ast::UintTy {
2268 UintTy::Usize => ast::UintTy::Usize,
2269 UintTy::U8 => ast::UintTy::U8,
2270 UintTy::U16 => ast::UintTy::U16,
2271 UintTy::U32 => ast::UintTy::U32,
2272 UintTy::U64 => ast::UintTy::U64,
2273 UintTy::U128 => ast::UintTy::U128,
2277 pub fn provide(providers: &mut ty::query::Providers) {
2278 closure::provide(providers);
2279 context::provide(providers);
2280 erase_regions::provide(providers);
2281 layout::provide(providers);
2282 util::provide(providers);
2283 print::provide(providers);
2284 super::util::bug::provide(providers);
2285 super::middle::provide(providers);
2286 *providers = ty::query::Providers {
2287 trait_impls_of: trait_def::trait_impls_of_provider,
2288 type_uninhabited_from: inhabitedness::type_uninhabited_from,
2289 const_param_default: consts::const_param_default,
2290 vtable_allocation: vtable::vtable_allocation_provider,
2295 /// A map for the local crate mapping each type to a vector of its
2296 /// inherent impls. This is not meant to be used outside of coherence;
2297 /// rather, you should request the vector for a specific type via
2298 /// `tcx.inherent_impls(def_id)` so as to minimize your dependencies
2299 /// (constructing this map requires touching the entire crate).
2300 #[derive(Clone, Debug, Default, HashStable)]
2301 pub struct CrateInherentImpls {
2302 pub inherent_impls: LocalDefIdMap<Vec<DefId>>,
2305 #[derive(Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash, TyEncodable, HashStable)]
2306 pub struct SymbolName<'tcx> {
2307 /// `&str` gives a consistent ordering, which ensures reproducible builds.
2308 pub name: &'tcx str,
2311 impl<'tcx> SymbolName<'tcx> {
2312 pub fn new(tcx: TyCtxt<'tcx>, name: &str) -> SymbolName<'tcx> {
2314 name: unsafe { str::from_utf8_unchecked(tcx.arena.alloc_slice(name.as_bytes())) },
2319 impl<'tcx> fmt::Display for SymbolName<'tcx> {
2320 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2321 fmt::Display::fmt(&self.name, fmt)
2325 impl<'tcx> fmt::Debug for SymbolName<'tcx> {
2326 fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
2327 fmt::Display::fmt(&self.name, fmt)
2331 #[derive(Debug, Default, Copy, Clone)]
2332 pub struct FoundRelationships {
2333 /// This is true if we identified that this Ty (`?T`) is found in a `?T: Foo`
2334 /// obligation, where:
2336 /// * `Foo` is not `Sized`
2337 /// * `(): Foo` may be satisfied
2338 pub self_in_trait: bool,
2339 /// This is true if we identified that this Ty (`?T`) is found in a `<_ as
2340 /// _>::AssocType = ?T`